content: /*
   * Copyright 2017 David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package hu.akarnokd.reactive4javaflow.impl.operators;
  
  import hu.akarnokd.reactive4javaflow.*;
  import hu.akarnokd.reactive4javaflow.errors.CompositeThrowable;
  import hu.akarnokd.reactive4javaflow.functionals.*;
  import hu.akarnokd.reactive4javaflow.fused.*;
  import hu.akarnokd.reactive4javaflow.impl.*;
  
  import java.lang.invoke.*;
  import java.util.Objects;
  import java.util.concurrent.*;
  
  public final class FolyamUsing<T, R> extends Folyam<T> {
  
      final Callable<R> resourceSupplier;
  
      final CheckedFunction<? super R, ? extends Flow.Publisher<? extends T>> flowSupplier;
  
      final CheckedConsumer<? super R> resourceCleanup;
  
      final boolean eager;
  
      public FolyamUsing(Callable<R> resourceSupplier, CheckedFunction<? super R, ? extends Flow.Publisher<? extends T>> flowSupplier, CheckedConsumer<? super R> resourceCleanup, boolean eager) {
          this.resourceSupplier = resourceSupplier;
          this.flowSupplier = flowSupplier;
          this.resourceCleanup = resourceCleanup;
          this.eager = eager;
      }
  
      @Override
      protected void subscribeActual(FolyamSubscriber<? super T> s) {
          R res;
  
          try {
              res = resourceSupplier.call();
          } catch (Throwable ex) {
              EmptySubscription.error(s, ex);
              return;
          }
  
          Flow.Publisher<? extends T> p;
  
          try {
              p = Objects.requireNonNull(flowSupplier.apply(res), "The flowSupplier returned a null Flow.Publisher");
          } catch (Throwable ex) {
              if (eager) {
                  try {
                      resourceCleanup.accept(res);
                  } catch (Throwable exc) {
                      ex = new CompositeThrowable(ex, exc);
                  }
                  EmptySubscription.error(s, ex);
              } else {
                  EmptySubscription.error(s, ex);
                  try {
                      resourceCleanup.accept(res);
                  } catch (Throwable exc) {
                      FolyamPlugins.onError(exc);
                  }
              }
              return;
          }
  
          if (s instanceof ConditionalSubscriber) {
              p.subscribe(new UsingConditionalSubscriber<>((ConditionalSubscriber<? super T>)s, res, resourceCleanup, eager));
          } else {
              p.subscribe(new UsingSubscriber<>(s, res, resourceCleanup, eager));
          }
      }
  
      static abstract class AbstractUsingSubscriber<T, R> implements FusedSubscription<T> {
  
          final R res;
  
          final CheckedConsumer<? super R> resourceCleanup;
  
          final boolean eager;
  
          Flow.Subscription upstream;
  
          FusedSubscription<T> qs;
  
          int fusionMode;
  
          boolean once;
          static final VarHandle ONCE = VH.find(MethodHandles.lookup(), AbstractUsingSubscriber.class, "once", Boolean.TYPE);
  
          protected AbstractUsingSubscriber(R res, CheckedConsumer<? super R> resourceCleanup, boolean eager) {
              this.res = res;
              this.resourceCleanup = resourceCleanup;
              this.eager = eager;
          }
          @Override
          public final int requestFusion(int mode) {
              FusedSubscription<T> fs = qs;
              if (fs != null) {
                  int m = fs.requestFusion(mode);
                  fusionMode = m;
                  return m;
              }
              return NONE;
          }
  
          @Override
          public final T poll() throws Throwable {
              T v = qs.poll();
              if (v == null && fusionMode == SYNC) {
                  if (eager) {
                      if (ONCE.compareAndSet(this, false, true)) {
                          resourceCleanup.accept(res);
                      }
                  } else {
                      cleanup();
                  }
              }
              return v;
          }
  
          @Override
          public final boolean isEmpty() {
              return qs.isEmpty();
          }
  
          @Override
          public final void clear() {
              qs.clear();
          }
  
          @SuppressWarnings("unchecked")
          public final void onSubscribe(Flow.Subscription subscription) {
              upstream = subscription;
              if (subscription instanceof FusedSubscription) {
                  this.qs = (FusedSubscription<T>)subscription;
              }
              onSubscribe();
          }
          @Override
          public final void request(long n) {
              upstream.request(n);
          }
  
          @Override
          public final void cancel() {
              if (eager) {
                  cleanup();
              }
              upstream.cancel();
              if (!eager) {
                  cleanup();
              }
          }
  
          abstract void onSubscribe();
  
          final void cleanup() {
              if (ONCE.compareAndSet(this, false, true)) {
                  try {
                      resourceCleanup.accept(res);
                  } catch (Throwable ex) {
                      FolyamPlugins.onError(ex);
                  }
              }
          }
      }
  
      static final class UsingSubscriber<T, R> extends AbstractUsingSubscriber<T, R> implements FolyamSubscriber<T> {
  
          final FolyamSubscriber<? super T> actual;
  
          UsingSubscriber(FolyamSubscriber<? super T> actual, R res, CheckedConsumer<? super R> resourceCleanup, boolean eager) {
              super(res, resourceCleanup, eager);
              this.actual = actual;
          }
  
          @Override
          void onSubscribe() {
              actual.onSubscribe(this);
          }
  
          @Override
          public void onNext(T item) {
              actual.onNext(item);
          }
  
          @Override
          public void onError(Throwable throwable) {
              if (eager) {
                  if (ONCE.compareAndSet(this, false, true)) {
                      try {
                          resourceCleanup.accept(res);
                      } catch (Throwable ex) {
                          throwable = new CompositeThrowable(throwable, ex);
                      }
                  }
              }
              actual.onError(throwable);
              if (!eager) {
                  cleanup();
              }
          }
  
          @Override
          public void onComplete() {
              if (eager) {
                  if (ONCE.compareAndSet(this, false, true)) {
                      try {
                          resourceCleanup.accept(res);
                      } catch (Throwable ex) {
                          actual.onError(ex);
                          return;
                      }
                  }
              }
              actual.onComplete();
              if (!eager) {
                  cleanup();
              }
          }
      }
  
  
      static final class UsingConditionalSubscriber<T, R> extends AbstractUsingSubscriber<T, R> implements ConditionalSubscriber<T> {
  
          final ConditionalSubscriber<? super T> actual;
  
          UsingConditionalSubscriber(ConditionalSubscriber<? super T> actual, R res, CheckedConsumer<? super R> resourceCleanup, boolean eager) {
              super(res, resourceCleanup, eager);
              this.actual = actual;
          }
  
          @Override
          void onSubscribe() {
              actual.onSubscribe(this);
          }
  
          @Override
          public void onNext(T item) {
              actual.onNext(item);
          }
  
          @Override
          public boolean tryOnNext(T item) {
              return actual.tryOnNext(item);
          }
  
          @Override
          public void onError(Throwable throwable) {
              if (eager) {
                  if (ONCE.compareAndSet(this, false, true)) {
                      try {
                          resourceCleanup.accept(res);
                      } catch (Throwable ex) {
                          throwable = new CompositeThrowable(throwable, ex);
                      }
                  }
              }
              actual.onError(throwable);
              if (!eager) {
                  cleanup();
              }
          }
  
          @Override
          public void onComplete() {
              if (eager) {
                  if (ONCE.compareAndSet(this, false, true)) {
                      try {
                          resourceCleanup.accept(res);
                      } catch (Throwable ex) {
                          actual.onError(ex);
                          return;
                      }
                  }
              }
              actual.onComplete();
              if (!eager) {
                  cleanup();
              }
          }
      }
  }
  